If you want to connect at home, with PI and PC connected to same router
connect to local IP address of PI server e.g. 192.168.1.4, not your external IP
when you go to your remote location, connect to external IP or no-ip address

does not work when client and server are connected
to same router and you try external IP address.

To get external access, Points to note
1) The PI needs a static internal IP address from the router.
Remember you forwarded port 1194 to some local IP address of PI server e.g. 192.168.1.4
so you need to make sure the PI always gets 192.168.1.4 after the router is rebooted.

2) Some domestic routers need to have the level of firewall paranoia/security lowered
so port forwarding works.

rpdom wrote:It looks like nmap is only showing TCP ports, but OpenVPN is listening on UDP, which is normal.

Make sure your router (if you have one) has port forwarding set so that UDP 1194 is directed to the IP address of your Pi.

That part is also set up correctly, because I can access other servers on the Pi externally (such as the webserver) which has port forwarding set up the same way as the VPN.

john564 wrote:If you want to connect at home, with PI and PC connected to same router
connect to local IP address of PI server e.g. 192.168.1.4, not your external IP
when you go to your remote location, connect to external IP or no-ip address

does not work when client and server are connected
to same router and you try external IP address.

To get external access, Points to note
1) The PI needs a static internal IP address from the router.
Remember you forwarded port 1194 to some local IP address of PI server e.g. 192.168.1.4
so you need to make sure the PI always gets 192.168.1.4 after the router is rebooted.

2) Some domestic routers need to have the level of firewall paranoia/security lowered
so port forwarding works.

I don't think that's the case, since I always test my VPN connection on my phone, over cellular. Additionally, I can access the other servers using the external address just fine from inside the network.

The problem is it was working but has stopped. I recently switched from Comcast to AT&T, so there was a period of time where the AT&T gateway and my router (Airport Extreme) were fighting over IP addresses. However, I fixed it so that the Airport (which was already setup with port forwarding and static IPs) was managing everything again. There shouldn't be any issues, at least as far as I can tell.